Polypropylene bumper cover composition

Abstract

This invention relates to a polypropylene bumper cover composition, particularly to a polypropylene bumper cover composition with improved contraction rate, painting properties, and molding properties. This composition includes 55 to 70 wt % of a polypropylene resin, 28 to 45 wt % of an ethylene-propylene rubber component, 2 to 5 wt % of an inorganic filler, 1 to 2.5 wt % of high density polyethylene, and 2.5 to 7 wt % of oxidation inhibitor, lubricant and carbon black. The ethylene-propylene rubber component may include two ethylene-propylene rubbers having different Mooney viscosities. The inorganic filler can be talc or fine talc.

What is claimed is: 
     
       1. A bumper cover composition comprising: 55 to 70 wt % of a polypropylene resin, 28 to 45 wt % of an ethylene-propylene rubber component, 2 to 5 wt % of an inorganic filler, 1 to 2.5 wt % of a high density polyethylene, and 2.5 to 7 wt % of an oxidation inhibitor, a lubricant and carbon black. 
     
     
       2. The composition according to claim 1, wherein said ethylene-propylene rubber component includes a first ethylene-propylene rubber material having a Mooney viscosity of 20R and a second ethylene-propylene rubber material having a Mooney viscosity of 70R, wherein the weight ratio of the first ethylene-propylene rubber material to the second ethylene-propylene rubber material is about 1:1. 
     
     
       3. The composition according to claim 1, wherein said inorganic filler is talc or fine talc. 
     
     
       4. The composition according to claim 2, wherein said inorganic filler is talc or fine talc. 
     
     
       5. The composition according to claim 1, wherein said ethylene-propylene rubber component includes a first ethylene-propylene rubber material and a second ethylene-propylene rubber material, wherein the first ethylene-propylene rubber material and the second ethylene-propylene rubber material have different viscosities. 
     
     
       6. The composition according to claim 5, wherein the weight ratio of the first ethylene-propylene rubber material to the second ethylene-propylene rubber material is about 1:1. 
     
     
       7. The composition according to claim 5, wherein said inorganic filler is talc or fine talc.